The invention relates to an apparatus on a spinning preparation machine, especially a flat card, roller card, cleaner or the like, with a cooling system, in which a roller has a cylindrical peripheral surface and a casing opposite to and spaced from this peripheral surface, a carding region where carding work is carried out and heat is generated being present between the peripheral surface of the roller and a part of the casing.
The spacings between the cylinder clothing and surfaces (counter-surfaces) located opposite it are of considerable importance in terms of machine engineering and fibre technology. The carding result, namely, cleaning, nep reduction and fibre shortening, is substantially dependent on the carding gap, that is, the spacing between the cylinder clothing and the clothings of the revolving and fixed flats. Routing of the airflow around the cylinder and heat dissipation are likewise dependent on the spacing between the cylinder clothing and opposing clothed or non-clothed surfaces, for example, separator blades or casing elements. The spacings are subject to various, in some cases oppositely directed, influences. The abrasion of opposing clothings leads to enlargement of the carding gap, which is associated with an increase in the number of neps and a decrease in fibre shortening. The consequence of an increase in cylinder speed, e.g. to enhance the cleaning action, is an expansion of the cylinder including the clothing owing to the centrifugal force, and hence a reduction in the carding gap. When processing large quantities of fibre and specific types of fibre, for example, synthetic fibres, the cylinder also expands, due to an increase of temperature, more than the rest of the machine around it, so that for this reason as well the spacings decrease. The machine elements, for example, fixed carding segments and/or separator blades, located radially opposite the cylinder also expand.
The carding gap is influenced in particular by the machine settings on the one hand and the state of the clothing on the other hand. The most important carding gap of the revolving flat card is located in the main carding zone, that is, between the cylinder and the revolving flat assembly. At least one clothing, which defines the operating distance of the carding zone as a whole, is in motion. In order to increase the production of the carding machine, one tries to select the operating speed of rotation or operating speed of the moving elements to be as high as the technology of fibre processing allows. The operating distance is located in the radial direction (starting from the axis of rotation) of the cylinder.
In the case of carding, increasingly larger amounts of fibre material per unit of time are being processed, which means higher speeds of the working elements and higher installed powers. With the working surface remaining constant, increasing throughput of fibre material (production) leads to greater generation of heat owing to the mechanical work. At the same time, however, the technological carding result (sliver uniformity, degree of cleaning, reduction of neps etc.) is continuously improved, which means more active surfaces engaged in carding, and settings of these active surfaces closer to the cylinder (drum). The proportion of synthetic fibres to be processed, with which, compared to cotton, more heat is generated through frictional contact with the active surfaces of the machine, is continually increasing. The working elements of high-performance carding machines are today fully enclosed all round in order to comply with safety standards, prevent particle emission into the spinning works environment and minimise the need for maintenance of the machines. Grids or even open, material-guiding surfaces that allow exchange of air belong to the past. The situations described appreciably increase the input of heat into the machine, whereas discharge of heat by means of convection drops appreciably. The resulting more marked heating of high-performance carding machines leads to greater thermoelastic deformation, which has an influence on the set spacings of the active surfaces owing to the uneven distribution of the temperature field: the spacings between cylinder and card top, doffer, fixed card tops and separation points equipped with blades decrease. In an extreme case the set gap between the active surfaces can close up completely, so that components moved relative to one another collide. The high-performance carding machine affected suffers considerable damage. Moreover, the generation of heat in the working region of the card can lead to different thermal expansion when the temperature difference between components is too great.
In the case of a known apparatus (EP-A-0 077 166), a liquid transport system is provided within the cylinder to balance the temperature conditions at the periphery of the cylinder. Two through-bored shaft journals are provided, through which a respective hose containing the liquid is routed. The hoses are connected to channels that are arranged along the inner peripheral surface of the cylinder. The cooling liquid enters and leaves on different sides of the cylinder. The known apparatus is extremely complex as regards its arrangement, both in relation to construction and assembly and also in relation to operation. The cooling liquid is admitted under pressure to the interior of the cylinder using an external pump. The rotary connection between the pump system and the roller cooling system requires especially careful construction and sealing to provide a reliable seal against leakage of the cooling liquid. The use of liquid in a spinning preparation machine is problematical and is avoided in practice. Complete canalisation of the cooling liquid is required, which leads to zoned cooling of the roller and hence to undesirable local deformation of the roller. Furthermore, it is problematic that the mass moment of inertia of the roller is undesirably changed, i.e. clearly increased, owing to the considerable amount of cooling liquid. This calls for a greater input power for the roller. In addition, the temperature of the liquid and/or of the roller is to be monitored, which requires further substantial outlay on apparatus. It is nevertheless impossible to achieve uniform temperature conditions and hence a constant carding gap.
It is an aim of the invention to produce an apparatus of the kind described in the introduction, which avoids or mitigates the said disadvantages, which in particular reduces or avoids thermal expansion of the roller in a structurally simple manner and allows a constant carding gap to be maintained.